1. Field of the Invention
The present invention relates to a multi-loop antenna module, in particular, to a multi-loop antenna module with wide beamwidth for providing good RF communications coverage.
2. Description of Related Art
The wireless LAN or 802.11a/b/g/n access-point antenna of the related art is almost of an external antenna structure. Common dipole antennas have a plastic or rubber sleeve covering thereon. In general, the dipole antenna is a single-band antenna for 2.4 GHz operation or a dual-band antenna for 2.4/5 GHz operation. The height of the dipole antenna is triple the thickness of the wireless broadband router/hub device, and one part of the dipole antenna is disposed on a side of the router and the rest of the dipole antenna is protruding from the top of the access-point or router housing. However, the protruded part of the dipole antenna can easily be vandalized by an outside force and also occupies space, which deteriorates the aesthetic appeal of the product, especially for the multi-antenna system.
When 2.4/5 GHz wireless LAN or 802.11a/b/g/n is applied to a dual-band antenna, the antenna has a one RF signal feeding port only. A typical dual-band access-point antenna is a dual-band dipole antenna that comprises two conductive copper tubes and uses a coaxial cable to achieve dual-band 2.4/5 GHz operation. However, the typical dual-band antenna needs a diplexer to simultaneously transmit and/or receive the 2.4 GHz and 5 GHz band signals to a 2.4 GHz module or a 5 GHz module, so that the cost would be increased, and the whole system loses extra gain or power.
Moreover, the related art provides another dual-band cross polarization dipole antenna that discloses a dual-antenna system. The dual-antenna system has two dual-band dipole antennas to generate two frequency bands for 2.4 GHz and 5 GHz operation. However, the antenna structure is of a stack structure, so that the height of the whole antenna structure is high.
Except for the above-mentioned defects, a wireless broadband access-point or router is usually installed on a ceiling, wall or table etc., so that different usage places require different types of antenna radiation patterns. For example, the access-point antenna installed on a ceiling needs to provide conical radiation patterns, the access-point antenna mounted on a wall needs to provide high directional radiation patterns, and the access-point antenna placed on a table needs to provide omnidirectional radiation patterns. However, radiation patterns generated by general antenna can only provide particular coverage, for example, a monopole antenna can only generate omnidirectional radiation patterns along a horizontal direction or conical radiation patterns along an elevation direction, and a patch or microstrip antenna can only provide broadside radiation patterns. That means that a general wireless broadband access-point or router antenna can only be applied to a particular place. In other words, if the access-point antenna is applied to a ceiling, the user cannot take the ceiling-mount access-point antenna for a wall mount access point. It is obvious that the access-point antenna generates different antenna radiation patterns and directions, according to different applications, so that the access-point antenna of the related art, if applied to a wrong place, will generate a communications dead zone to decrease RF signal receiving efficiency and signal transmitting quality.